Time grating linear displacement sensor based on alternating light field

Abstract

A time grating linear displacement sensor based on an alternating light field, comprising a fixed pole plate and a movable pole plate, wherein the upper part and the lower part of the fixed pole plate are respectively provided with a row of square fixed pole plate light-transmitting surfaces which are uniformly distributed; the upper part and the lower part at the rear of the fixed pole plate are respectively provided with one group of light-emitting devices; the upper part and the lower part of the movable pole plate are respectively provided with two semi-sinusoidal movable pole plate light-transmitting surfaces; and four light-sensitive receiving units are fixed on the movable pole plate, the photoelectric receiving surfaces of the light-sensitive receiving units covering the movable pole plate light-transmitting surfaces. The two groups of light-emitting devices respectively provide an alternating light field. The movable pole plate moves relative to the fixed pole plate.

What is claimed is: 
     
       1. A time grating linear displacement sensor based on alternating light field, comprising:
 a fixed pole plate; and 
 a movable pole plate; 
 wherein the fixed pole plate and the movable pole plate are arranged in parallel positions and a space is left therebetween; 
 wherein an upper part and a lower part of the fixed pole plate are respectively provided with a row of square shaped fixed pole plate light transmitting surfaces that are uniformly distributed thereon, wherein a starting position of the row of fixed pole plate light transmitting surfaces located on the upper part of the fixed pole plate has a difference equal to one-half of the width of one fixed pole plate light transmitting surface from a starting position of the row of fixed pole plate light transmitting surfaces located on the lower part of the fixed pole plate; 
 wherein in a row of fixed pole plate light transmitting surfaces, a distance between two neighboring fixed pole plate light transmitting surfaces is equal to the width of one fixed pole plate light transmitting surface; 
 wherein each one of a rear upper position and a rear lower position of the fixed pole plate is provided with a group of non-interfering light emitting devices; 
 wherein an upper part and a lower part of the movable pole plate are respectively provided with two semi-sinusoidal movable pole plate light transmitting surfaces, wherein the movable pole plate light transmitting surfaces are directly facing the fixed pole plate light transmitting surfaces, a width of the movable pole plate light transmitting surface is equal to a width of the fixed pole plate light transmitting surface, a height of the movable pole plate light transmitting surface is less than one-half of a height of the fixed pole plate light transmitting surface, an arrangement manner of the two movable pole plate light transmitting surfaces located on the lower part of the movable pole plate is the same as an arrangement manner of the two movable pole plate light transmitting surfaces located on the upper part of the movable pole plate, and a starting position of the two movable pole plate light transmitting surfaces located on the lower part of the movable pole plate is aligned with a starting position of the two movable pole plate light transmitting surfaces located on the upper part of the movable pole plate, the respective starting positions of the two movable pole plate light transmitting surfaces located on the upper part of the movable pole plate has an interval distance of a width of one movable pole plate light transmitting surface along a direction of the width of the movable pole plate, and an interval distance between the two movable pole plate light transmitting surfaces located on the upper part of the movable pole plate along a direction of the height of the movable pole plate is greater than the height of one movable pole plate light transmitting surface and less than one-half of the height of one fixed pole plate light transmitting surface; 
 wherein four light sensitive receiving units, which correspond to the four movable pole plate light transmitting surfaces, are fixed on the movable pole plate, and photoelectric receiving surfaces of the four light sensitive receiving units cover the corresponding movable pole plate light transmitting surfaces, a terminal of one of the two light sensitive receiving units fixed on the upper part of the movable pole plate and a terminal with the same potential polarity of the other one of the two light sensitive receiving units fixed on the upper part of the movable pole plate are shorted, moreover, the remaining two terminals of the two light sensitive receiving units fixed on the upper part of the movable pole plate are used as respective electrical signal output terminals, a terminal of one of the two light sensitive receiving units fixed on the lower part of the movable pole plate and a terminal with the same potential polarity of the other one of the two light sensitive receiving units fixed on the lower part of the movable pole plate are shorted, the remaining two terminals of the two light sensitive receiving units fixed on the lower part of the movable pole plate are used as respective electrical signal output terminals; 
 wherein the two groups of light emitting devices respectively provide equal amplitude and equal frequency alternating light fields whose light intensities change according to sine and cosine laws, respectively; 
 wherein the alternating light source generates equally distributed upper and lower two rows of alternating light fields on a surface of the fixed pole plate, whose light intensities change according to sine or cosine law, the movable pole plate moves relative to the fixed pole plate, the four light sensitive receiving units output electrical signals that are representing corresponding luminous fluxes changes through the movable pole plate light transmitting surfaces, which, following a differencing calculation, generate light field coupled signals Uoa and Uob, which are respectively corresponding to differential changes in light transmitting areas of the two movable pole plate light transmitting surfaces, the two coupled signals are further combined into one path of traveling wave signal Uo by an adding circuit, the traveling wave signal Uo and a path of reference signal Ur with equal frequency and a fixed phase respectively undergo a shaping process using a shaping circuit, and then a phase comparison process using a phase comparison circuit, the phase difference between the two paths of signals is represented by the number of interpolated high frequency clock pulses, subsequently through a corresponding scale transformation, a value of linear displacement of the movable pole plate relative to the fixed pole plate is thus obtained. 
 
     
     
       2. The time grating linear displacement sensor based on alternating light field as set forth in  claim 1 , wherein the light emitting devices are side light optical fiber or semiconductor surface light source, which are fixedly mounted to the rear upper and rear lower parts of the fixed pole plate, and two sinusoidal excitation power sources with equal amplitude and equal frequency and ninety degrees in phase difference respectively drive two semiconductor laser generators to illuminate on two groups of side light optical fiber or semiconductor surface light sources, so as to generate the alternating light source. 
     
     
       3. The time grating linear displacement sensor based on alternating light field as set forth in  claim 1 , wherein the light sensitive receiving units are photocells or SMD photosensitive diode. 
     
     
       4. The time grating linear displacement sensor based on alternating light field as set forth in  claim 1 , wherein the electrical signals outputted by the two light sensitive receiving units fixed on the upper part of the movable pole plate undergo a differencing process through a first differential amplifier circuit to reach the light field coupled signal Uoa; and the electrical signals outputted by the two light sensitive receiving units fixed on the lower part of the movable pole plate undergo a differencing process through a second differential amplifier circuit to reach the light field coupled signal Uob. 
     
     
       5. The time grating linear displacement sensor based on alternating light field as set forth in  claim 1 , wherein the traveling wave signal Uo and the equal frequency reference signal Ur undergo a shaping process through the shaping circuit to form respective square waves, and then undergo a phase comparison process to obtain the value of the linear displacement of the movable pole plate relative to the fixed pole plate by way of calculating a time difference of the two square waves passing the zero point.